In recent years, flat panel displays have been popular in a variety of fields because of their light weight and high energy efficiency, and liquid crystal displays (LCDs) are the most common among them. According to the operating modes of the liquid crystals, LCD panels mainly include the following types: a Twisted Nematic (TN) type, an In-plane Switching (IPS) type, and a Fringe Field Switching (FFS) type, etc.
When a horizontal electric field is used to drive both the FFS type and the IPS type, the FFS type has been proven to achieve high resolution and wide viewing angles in LCDs, and performs better than the IPS type. This is because the FFS type can freely include an even or odd number of liquid crystal domains, which breaks the limitation of even number of liquid crystal domains in the IPS type and enables high quality images in high resolution LCDs.
FIG. 1 illustrates a top view of pixel units in a conventional FFS mode LCD panel. The FFS mode LCD panel includes a plurality of scanning lines 101, a plurality of data lines 102, and a plurality of pixel units confined by the adjacent scanning lines 101 and data lines 102. The pixel units include common electrodes 104 and pixel electrodes 105 disposed on top of the common electrode 104 but insulated. The common electrode 104 is a planar electrode, and the pixel electrode 105 is a comb-shaped electrode having a plurality of stripe-shaped electrodes.
Further, the pixel unit includes a plurality of thin film transistors (TFT) 103 disposed at the crossing of the scanning lines 101 and the data lines 102. The TFT 103 has a gate electrically connected to the scanning line 101, a source (or drain) electrically connected to the data line 102, and a drain (or source) electrically connected to the pixel electrode 105. In the pixel units shown in FIG. 1, the pixel electrodes 105, the common electrodes 104 and the data lines 102 are insulated from each other (the insulating layers are not show in FIG. 1). The pixel electrodes 105 are disposed on top of the common electrodes. 104. In the light transmitting direction, a black matrix having a plurality of black stripes (not shown in FIG. 1) is disposed on top of the scanning lines 101 and data lines 102. A plurality of color barriers are disposed among adjacent black stripes in the black matrix. Each color barrier corresponds to each pixel unit to display various colors.
However, the above FFS mode LCD panel may have a color shift problem. Due to the resolution limitation of photo-lithography machines, it is difficult to reduce the stripe-shaped electrode width and the gap between two adjacent stripe-shaped electrodes. The pixel unit have a limited width and, therefore, the stripe-shaped electrodes in one pixel unit may be very close to the stripe-shaped electrodes in the adjacent pixel units. When a voltage is applied to the stripe-shaped electrodes in one pixel unit, liquid crystal molecules in the adjacent pixel units may be also driven to rotate. If the adjacent pixel units display different colors, a color mixing may occur, which means a noticeable color shift in terms of visual effects.
FIG. 2 illustrates a top view of pixel units in another conventional FFS mode LCD panel. The pixel electrode 105 include one stripe-shaped electrode. Such a design may be less likely to have a color shift problem. However, under such design, the ability to drive the liquid crystal molecules may be reduced, and the transmittance of the LCD panel may be decreased accordingly.
The disclosed pixel unit array and liquid crystal display device thereof are directed to solve one or more problems in the art.